patch 8.0.0171: JS style JSON does not support single quotes

Problem:    JS style JSON does not support single quotes.
Solution:   Allow for single quotes. (Yasuhiro Matsumoto, closes #1371)
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index b3c7323..a53b5d2 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -5229,6 +5229,7 @@
 js_decode({string})					*js_decode()*
 		This is similar to |json_decode()| with these differences:
 		- Object key names do not have to be in quotes.
+		- Strings can be in single quotes.
 		- Empty items in an array (between two commas) are allowed and
 		  result in v:none items.
 
diff --git a/src/json.c b/src/json.c
index 2cc3a2a..faaeab3 100644
--- a/src/json.c
+++ b/src/json.c
@@ -378,7 +378,7 @@
 }
 
     static int
-json_decode_string(js_read_T *reader, typval_T *res)
+json_decode_string(js_read_T *reader, typval_T *res, int quote)
 {
     garray_T    ga;
     int		len;
@@ -389,8 +389,8 @@
     if (res != NULL)
 	ga_init2(&ga, 1, 200);
 
-    p = reader->js_buf + reader->js_used + 1; /* skip over " */
-    while (*p != '"')
+    p = reader->js_buf + reader->js_used + 1; /* skip over " or ' */
+    while (*p != quote)
     {
 	/* The JSON is always expected to be utf-8, thus use utf functions
 	 * here. The string is converted below if needed. */
@@ -504,7 +504,7 @@
     }
 
     reader->js_used = (int)(p - reader->js_buf);
-    if (*p == '"')
+    if (*p == quote)
     {
 	++reader->js_used;
 	if (res != NULL)
@@ -620,7 +620,8 @@
 
 	if (top_item != NULL && top_item->jd_type == JSON_OBJECT_KEY
 		&& (options & JSON_JS)
-		&& reader->js_buf[reader->js_used] != '"')
+		&& reader->js_buf[reader->js_used] != '"'
+		&& reader->js_buf[reader->js_used] != '\'')
 	{
 	    char_u *key;
 
@@ -690,7 +691,17 @@
 		    continue;
 
 		case '"': /* string */
-		    retval = json_decode_string(reader, cur_item);
+		    retval = json_decode_string(reader, cur_item, *p);
+		    break;
+
+		case '\'':
+		    if (options & JSON_JS)
+			retval = json_decode_string(reader, cur_item, *p);
+		    else
+		    {
+			EMSG(_(e_invarg));
+			retval = FAIL;
+		    }
 		    break;
 
 		case ',': /* comma: empty item */
diff --git a/src/json_test.c b/src/json_test.c
index 1a1fdcb..74463f3 100644
--- a/src/json_test.c
+++ b/src/json_test.c
@@ -181,7 +181,7 @@
     reader.js_buf = (char_u *)" \"foo";
     reader.js_end = reader.js_buf + STRLEN(reader.js_buf);
     reader.js_cookie =        " \"foobar\"  ";
-    assert(json_decode_string(&reader, NULL) == OK);
+    assert(json_decode_string(&reader, NULL, '"') == OK);
 }
 #endif
 
diff --git a/src/testdir/test_json.vim b/src/testdir/test_json.vim
index ecca038..bd348fc 100644
--- a/src/testdir/test_json.vim
+++ b/src/testdir/test_json.vim
@@ -145,6 +145,8 @@
   call assert_equal("", json_decode('""'))
 
   call assert_equal({'n': 1}, json_decode('{"n":1,}'))
+  call assert_fails("call json_decode(\"{'n':'1',}\")", 'E474:')
+  call assert_fails("call json_decode(\"'n'\")", 'E474:')
 
   call assert_fails('call json_decode("\"")', "E474:")
   call assert_fails('call json_decode("blah")', "E474:")
@@ -255,8 +257,11 @@
   call assert_equal(v:none, js_decode(''))
   call assert_equal(type(v:none), type(js_decode('')))
   call assert_equal("", js_decode('""'))
+  call assert_equal("", js_decode("''"))
 
+  call assert_equal('n', js_decode("'n'"))
   call assert_equal({'n': 1}, js_decode('{"n":1,}'))
+  call assert_equal({'n': '1'}, js_decode("{'n':'1',}"))
 
   call assert_fails('call js_decode("\"")', "E474:")
   call assert_fails('call js_decode("blah")', "E474:")
diff --git a/src/version.c b/src/version.c
index 4bc287f..dfbbe18 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    171,
+/**/
     170,
 /**/
     169,